KSC Glock 17 hopup metal ball.....
 

Does anybody know where do find a replacement?

Or anybody know the exact size of it? (in mm)

I need a help here, thanks.

I lost mine way back and was never able to find a replacement. Every place I did see it online was listed as out of stock.

However, I did make my own with a small solder bead, and the gun works flawlessly. It's my most accurate pistol despite that.

a solder bead?? could you measure yours? because I've tried to make my own solder bead too but they were just too big or small...I think I've made about at least 15 of them tried...

Lost mine as well, KWA M93RII
Surprisingly it does shoot straight enough without it

You can probably order one from KWA USA's proshop though
I didn't want to get into the hassle of calling and all; it's the only real reason I haven't ordered one yet; last time I checked it was in stock (along with hopup rubber)

I have no way of measuring that dude. I say just experiment until you get one the right size. I had 3 tries at it before I found one on my iron cleaning sponge that happened to work perfectly.

What a hassle it is.....I guess I'll have to start making solder beads again...

Melt solder on your iron then drag it on a wet sponge. You'll get beads of different sizes.

Weird bit of trivia. One of the older IKEA dressers (from a couple of years ago) had bearings in the roller arms that are the exact, same size BBs as the one that KSC uses for their hopup BB.

If you drop by your local IKEA in the service/parts department you might be able to find a set of those slider/roller arms with the BBs if you take it apart for about $5/set or so iirc.

You can also go to a hobby shop and buy a AE RC18 ball differential rebuild kit... they are about 2$ and come with 8 BBs

This. I never worry about losing the balls now.